1. Field of the Invention
The present invention relates to an optical switch of a transparent material in which a three-dimensional diffraction pattern is recorded.
2. Background Information
In the simplest case, optical switches are used to deflect a single light beam either in a direction A or in a direction B. By the switching action, the light beam is directed either toward a receiver A' in direction A or toward a receiver B' in direction B. The light beam can thus be switched between the receivers A' and B'. In another, even simpler optical switch, the light beam is either passed or reflected, so that it can be turned on or off in the direction of a single receiver A'. As part of such a switch which deflects the light beam in a first or second direction, a hologram is especially suited.
From APPLIED OPTICS Vol. 27, no. 20 (1988), pp. 4244 to 4250, an optical switch ("Holoswitch") is known which comprises an array of liquid crystal cells and polarizing beam splitters, as well as a plane arrangement of holograms.
In the optical switch, one liquid crystal cell, one beam splitter, and one hologram are respectively associated with one another. The holograms form invariable, predetermined diffraction patterns.
Each of the liquid crystal cells deflects a bundle of light beams, generated by, e.g., several laser sources, toward one of the holograms, which deflects the light beams toward an associated detector.
The liquid crystal cells are electrically controlled devices. They switch between two mutually perpendicular polarization states in the light beams, according to the voltage applied to them. The beam splitters, which follow the liquid crystal cells in the direction of transmission of the light beams, transmit or reflect the light beams depending on the state of polarization. Thus, the light beams pass through the liquid crystal cell and the beam splitter before reaching the respective hologram.
This prior art optical switch is constructed in an aluminum box, measuring 19 by 19 by 23 cm, which also contains support structures. This means that the optical switch takes up considerable space.
In addition, the change between the two polarization states in the liquid crystal cells limits the switching speed of this optical switch.